1. Field of the Invention
The present invention relates to a pressurized gas dispensing device, to an assembly comprising such a dispensing device and a control device and to a container provided with such a dispensing device.
The invention relates more specifically to a device for dispensing pressurized gas, such as a tap, comprising a first end intended to be placed in the orifice of a pressurized-gas storage reservoir, and a second end comprising a connection interface that can be connected selectively to a device for controlling the filling and/or the withdrawing of gas from the reservoir, the dispensing device comprising an internal gas circuit having an upstream end intended to communicate with the inside of the reservoir and a downstream end intended to be connected to the said filling and/or withdrawing control device, the internal circuit comprising, in series, from the upstream end downstream, a pressure regulator and a downstream isolation valve, that portion of the internal circuit that lies between the pressure regulator and the downstream isolation valve defining a chamber known as the low-pressure chamber.
2. Related Art
For safety reasons in particular, gas filling and dispensing systems such as taps with in-built regulators are designed so that the end-user of a pressurized-gas cylinder cannot come into contact with the gas at the high pressure of the cylinder but rather only with gas at a pressure that has been reduced by a pressure regulator.
When a valve is fitted downstream of the regulator (on the low-pressure side) an increase in pressure may occur between the regulator and the isolation valve, particularly if the regulator leaks. In particular, no regulator can be considered to be 100% fluidtight, especially in respect of gases with small molecules (of the hydrogen or helium type).
Thus, if the gas is stored for lengthy periods without any gas being withdrawn, the low-pressure chamber downstream of the regulator may fill with gas at a high pressure. When this happens, it creates a situation that is dangerous when the user wishes to withdraw some gas again and connects to the reservoir by opening the isolation valve (via a quick connector for example).
Thus, when the user connects to the withdrawing port and there is an abnormally high pressure upstream of the isolation valve, there is a risk that this will cause the o-rings that seal between the withdrawing port and the quick connector of the user system to become extruded.
Safety problems arise especially in the case where the tap has a filling orifice that is common with the withdrawing orifice.
In order to solve this problem, it is known practice to use safety venting valves which release gas in the event of an overpressure or an excessive temperature. However, even if the leaks are relatively small, under certain situations these known vent valves may also give rise to dangerous situations by suddenly releasing a sizable amount of gas. This is particularly dangerous when the gas is flammable, like hydrogen.
For these reasons, in certain applications, provision may be made for the vent gas released by the safety release valve to be kept in a sealed volume inside the tap. The vent gas is then processed and discharged by a safety system that can be connected to the tap.
Another solution may involve indicating to the user (via a pressure gauge) that the pressure in the tap just behind the valve that isolates it from the outside is abnormally high. However, this approach is not reliable because its safety aspects are entirely reliant upon the user.
It is an object of the present invention to alleviate all or some of the abovementioned disadvantages of the prior art.